The invention relates generally to welders, and more particularly to a welder configured to perform a preheating operation on welding wire prior to execution of a weld.
A wide range of welding systems and welding control regimes have been implemented for various purposes. In continuous welding operations, metal inert gas (MIG) techniques allow for formation of a continuing weld bead by feeding welding wire shielded by inert gas from a welding torch. Electrical power is applied to the welding wire and a circuit is completed through the workpiece to sustain an arc that melts the wire and the workpiece to form the desired weld.
Advanced forms of MIG welding are based upon generation of pulsed power in the welding power supply. That is, various pulsed regimes may be carried out in which current and/or voltage pulses are commanded by the power supply control circuitry to regulate the formation and deposition of metal droplets from the welding wire, to sustain a desired heating and cooling profile of the weld pool, to control shorting between the wire and the weld pool, and so forth. However other welding regimes exist and are commonly used that provide power that is not pulsed. The various regimes may rely on “electrode positive” or “electrode negative” polarities, and the present disclosure may relate to any and all of these.
While very effective in many applications, MIG welding techniques may experience different initial welding performance based upon whether the weld is started with the electrode “cold” or “hot”. In general, a cold electrode start may be considered a start in which the electrode tip and adjacent metals are at or relatively near the ambient temperature. Hot electrode starts, by contrast, are typically those in which the electrode tip and adjacent metals are much more elevated, but below the melting point of the electrode wire. In some applications, it is believed that initiation of arcs and welds is facilitated when the electrode is hot. However, the current state of the art does not provide regimes designed to ensure that the electrode is heated prior to initiate of welds.
There is a need, therefore, for improved welding strategies that allow for welding initiation with a heated electrode so as to improve weld performance.